I'm interested to learn more on this subject as well. My main power source and welder is a 89 miller legend aead 200le that I've been running stick off of since 92, love that machine. It's very similar to your E2, which also had he 100hz outlet, and lower rpms than most generator welders. I was recently given a HF250D-1 high freq box, a water cooled torch, and got all the fixin's for pedal tig, only wish I'd taken up tig years ago.
Getting it all to run with a foot pedal (basically just tapping the fine current rheostat to a pedal) took some doing, so I have been trying to study up a bit on how these machines function.
Along with this years upgrades I just got a millermatic 130 for thin gauge work, which I tend to avoid, if 3/32 6013 blows holes it gets touchy for me.
Also been reading up on using voltage sensing feeders like the miller 12vs, in use with CC power sources, and to tie this line of thinking with the thread, I'd really like to put a clamp on ammeter and a volt meter on my welding leads, and run some beads in the different course current settings, and try the fine current control at both extremes and see just what is going on with the volt/amp curves in action. I do understand that voltage is variable in SMAW welding, might be worth renting or borrowing a 12vs to see what happens.
If anyone has a good grasp of what I'm likely to see, or has links to more info I'd love to hear about it.
PS, in regards to the last post about he bobcat welder, I think it s a different critter than the AEAD, the generator looks a lot different. Anyone know anything about the constant voltage adapter that was avalable for the SA-200s? I noticed in the miller literature that CV boxes were available for some miller gen welders too. Interesting....